package cn.sanshuilin.kst.common.upload.util;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Random;

public class MD5Util {
	// 全局数组
    private final static String[] strDigits = { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };

    public MD5Util() {

    }

    // 返回形式为数字跟字符串
    private static String byteToArrayString(byte bByte) {
        int iRet = bByte;
        if (iRet < 0) {
            iRet += 256;
        }
        int iD1 = iRet / 16;
        int iD2 = iRet % 16;
        return strDigits[iD1] + strDigits[iD2];
    }

    // 返回形式只为数字
    @SuppressWarnings("unused")
    private static String byteToNum(byte bByte) {
        int iRet = bByte;
        if (iRet < 0) {
            iRet += 256;
        }
        return String.valueOf(iRet);
    }

    // 转换字节数组为16进制字串
    private static String byteToString(byte[] bByte) {
        StringBuffer sBuffer = new StringBuffer();
        for (int i = 0; i < bByte.length; i++) {
            sBuffer.append(byteToArrayString(bByte[i]));
        }
        return sBuffer.toString();
    }

    public static String GetMD5Code(String strObj) {
        String resultString = null;
        try {
            resultString = new String(strObj);
            MessageDigest md = MessageDigest.getInstance("MD5");
            // md.digest() 该函数返回值为存放哈希值结果的byte数组
            resultString = byteToString(md.digest(strObj.getBytes()));
        } catch (NoSuchAlgorithmException ex) {
            ex.printStackTrace();
        }
        return resultString;
    }
    
    public static String random(int n) {
		if (n < 1 || n > 10) {
			throw new IllegalArgumentException("cannot random " + n + " bit number");
		}
		Random ran = new Random();
		if (n == 1) {
			return String.valueOf(ran.nextInt(10));
		}
		int bitField = 0;
		char[] chs = new char[n];
		for (int i = 0; i < n; i++) {
			while (true) {
				int k = ran.nextInt(10);
				if ((bitField & (1 << k)) == 0) {
					bitField |= 1 << k;
					chs[i] = (char) (k + '0');
					break;
				}
			}
		}
		return new String(chs);
	}
    public static void main(String[] args) {
    	System.out.println(GetMD5Code("123456"));
	}
}
